Purpose :
To document and describe the microscopic lesions in the aqueous drainage structures of 43 dogs of 8 breeds diagnosed with primary lens luxation (PLL) associated with a mutation on the ADAMTS17 gene.

Methods :
The Comparative Ocular Pathology Laboratory of Wisconsin database identified 158 dogs diagnosed with PLL. The diagnosis was based on the microscopic identification of the pathognomonic zonular ligament dysplastic (ZLD) lesions. Cases with moderate to severe intraocular hemorrhage, fibrovascular membranes, peripheral anterior synechiae, posterior synechiae, endophthalmitis, substantial corneal disease or other major lesions considered unrelated to PLL were excluded. All cases had been formalin fixed, paraffin embedded, parasagittally sectioned at 4 μM and H&E stained. Seventeen of these cases were stained with Alcian blue and PAS.

Results :
Forty-four eyes from 43 dogs met our inclusion criteria. Eighteen of these cases were Jack Russell Terriers and 9 were beagle dogs from a primary open angle glaucoma colony diagnosed with PLL and a mutation on the ADAMTS10 gene. The remaining breeds were Australian cattle dog (n=5), Shar pei (n=4), rat terrier (n=2), blue heeler (n=2), toy fox terrier (n=1), miniature schnauzer (n=1) and unspecified breed (n=1). The median age was 6 years (range 0.5-13 years). The most common phenotype observed was an open angle/ciliary cleft with deposition of a pale eosinophilic extracellular matrix (ECM) within the corneoscleral trabecular meshwork (TM) beams causing variable degrees of meshwork collapsed (n=29). This matrix was granular and lightly Alcian blue and PAS-positive, with similar morphology to the dysplastic zonular matrix carpeting the ciliary body surfaces. Nineteen cases had pigment dispersion within the TM and 16 cases had corneoscleral TM tissue prolapsed into the adjacent collector channels. Eighteen cases had two concurrent lesions and 4 cases had all 3 lesions.

Conclusions :
We observed for the first time ECM-related lesions on the aqueous drainage structures of dogs with PLL. The pathologic ECM observed in the TM morphologically resembles the dysplastic zonular fibers seen on the ciliary body surfaces. These findings open the possibility to the presence of other ECM-related lesions in ocular tissues other than the zonular fibers in PLL and that these lesions might also contribute to the development of glaucoma in these dogs.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.